Fluid pressure actuated switches



March 29, 1966. F, MAZZEQ 3,243,539

FLUID PRESSURE ACTUATED SWITCHES Filed June 5, 1964 2 Sheets-Sheet 1 ZNVENTOR CHARLES F. MAZZEO March 29,1966 S c F, MAZZEQ 3,243,539

FLUID PRESSURE ACTUATED SWITCHES Filed June 5, 1964 S 2 Sheets-Sheet 2 CHARLES F. MAZZEO F|g v BY @Z%EY INVENTOR United States Patent 3,243,539 FLUID PRESSURE ACTUATED SWITCHES Charles F. Mazzeo, Scotch Plains, N.J., asslgnor to The Wilcolator Company, Elizabeth, N.J., a corporation of New Jersey Filed June 3, 1964, Ser. No. 372,215 7 Claims. (Cl. 20083) This invention relates to fluid pressure actuated switches of the type having expansible power means connected to a switch casing in predetermined operative relation to a switch operating member, and more particularly to improvements in construction of such switches by which precise relative positions of the switch operating member and the power means are maintained in spite of alterations in dimensions of the casing or parts of the power element connected to the casing due to changes in ambient tem perature or from shrinkage of the casing for any reason whereby the repetitive operating characteristics and operational reliability of the switch are constant throughout the life thereof.

It is an object of this invention to provide a pressure operated switch of the foregoing character comprising a switch containing casing formed of an insulating material such as Bakelite having a power means, such as an expansible diaphragm assembly, secured thereto in operative relation with the switch, the power means being secured in a predetermined seated relation on the casing by a resilient clamping member acting between a shoulder on the insulating casing and the power means, whereby although the insulating casing proper may expand or contract with respect to the power means structure, the re silient clamping member maintains the predetermined seating relation of the power means on the casing.

Another object of this invention is the provision of an improved fluid pressure actuated switch of the type referred to hereinbefore wherein spring loading means acts against the expansible power means with a force tending to urge the insulating switch casing from its seated relation thereto and wherein the resilient clamping member urges the insulating casing into the seated relation with a force greater than that exerted by the spring loading means.

Yet another object of this invention is the provision of an improved fluid pressure actuated switch as described in the preceding paragraphs and wherein the clamping member comprises an inexpensive annular sheet metal spring member receiving the insulating casing so that the inner edges of the spring member bear against the shoulder edges of the casing, and the outer edges of the clamping member are secured to the outer edge of an annular flange projecting radially from the power element and spaced from the inner portion of the spring member so that the spring member at all times biases the casing and power means into the seating relationship desired. The invention may be further said to reside in certain construction and arrangements of parts by which the foregoing objects and advantages as well as others are achieved, as will be readily understood from the following detailed description of a preferred fluid pressure actuated switch embodying the invention, read in conjunction with the accompanying sheets of drawings forming a part of this specification, and in which:

FIG. 1 is a top plan view of a fluid pressure operated switch embodying the invention;

FIG. 2 is a bottom View of the switch of FIG. 1;

FIG. 3 is a sectional view taken substantially along lines 33 of FIG. 1;

FIG. 4 is a fragmentary sectional view of the switch taken substantially along line 44 of FIG. 3; and

FIG. 5 is an exploded perspective view of the switch illustrating certain parts thereof prior to assembly.

Patented Mar. 29, 1966 In the form of the invention illustrated in the drawings and described hereinafter, there is provided a fluid pressure operated switch generally indicated at 10 and comprising a hollow, cup-shaped switch casing 11 which is formed of a rigid, electrically insulating material such as Bakelite and is generally cylindrical in configuration. The casing 11 is provided with an annular shoulder 12 defined by a flange or rim extending about the open end thereof, the purpose of which shoulder will become apparent as the description proceeds. The closed end of the casing 11 is characterized by two wedge shaped depressions or recesses 13, each of which accommodates one of a pair of conductor members 14 and 15.

As is best seen in FIG. 4, the pair of conductor members 14 and 15 extend from the exterior of the casing 11 to the interior thereof, the outer end of the conductor member 14 being formed at right angles to provide a blade type terminal 14a, and the outer end of the conductor member 15 being formed to provide a terminal 15a. The conductor member 14 is secured to the casing 11 as by rivet l6 and 17, while the conductor member 15 is secured to the casing as by rivets 18 and 19. Clamped between the conductor member 14 and the casing 11 is one end 20a of a U-shaped switch arm 20 which is formed of a resilient, conductive spring metal such as beryllium copper, and carries at its free end a movable contact 21. The movable contact 21 is in registration with a fixed contact 22 secured on the conductor member 15, and is normally separated therefrom by the inherent springiness of the switch arm 20.

A switch operating plunger 25 has a reduced end portion 25a extending through an opening in the switch arm 20 and is axially movable against that arm to effect closing of the contacts 21, 22. The opposite end' 25b of the plunger 25 is reduced and extends through a central opening in a glass laminate dielectric disc 27 which rests against inwardly directed shoulders 28 in the casing 11. The disc 27 thereby serves to guide the plunger 25 in its axial movements.

Inward movement of the switch operating plunger 25 to effect closing of the contacts 21, 22 is effected by a power means comprising a diaphragm assembly generally indicated at 30. The diaphragm assembly comprises a cover member 31 in the form of a relatively rigid sheet metal stamping having a cylindrical side wall portion 31a, a dished, circular end wall 31b, and an oval flange 31c extending laterally from the edge of the cylindrical wall 31a. The flange 310 is conveniently provided with diametrically disposed apertures 32 for receiving screws or other fasteners for mounting the switch device 10 to a suitable support structure, not shown. A flexible metal diaphragm 33 is welded about its periphery to the end wall 31b of the cover member 31 near the junction of the end wall with the cylindrical wall 31a. The flexible diaphragm 33 and the end wall 31b define therebetween an expansible chamber 35 which communicates through an opening 36 in the end wall with a capillary tube 37 secured in a nipple 38 fixed to the end wall. The capillary tube 37 and chamber 35 may form part of a closed system containing a thermally expansible fluid such as liquid mercury, so that upon expansion of such fluid in response to an increase in temperature thereof, the diaphragm 30 will be flexed away from the Wall 3112 and move plunger 25 to close contacts 21, 22. In the present example the diaphragm 33 is preferably of the snap acting type well known to those skilled in the art to which the invention" pertains.

As is best seen in FIG. 3 the peripheral portion of the diaphragm where it is welded to the cover member 31 provides an annular seat 40 in the diaphragm assembly, and the switch 11 has its open end nested in the cover member 31 of the diaphragm assembly with the axially directed edge or bearing surface 41 thereof bearing against seat 40.

The switch casing 11 and diaphragm assembly are secured in seated relation by a clamp member 45 which has a peripheral outline substantially corresponding to that of the flange 310 of the covered member 31. The clamp 45 is formed of flat spring metal, preferably as a sheet metal stamping, and is provided with a central opening 46 which receives the upper portion of casing 11; however, the radially extending shoulder 12 of the casing 11 is of larger diameter than opening 46 so that the inner edge of the clamp member bears against the shoulder. The cover clamp 4-5 is further provided with a plurality of tabs 45a extending from the periphery of the cover clamp, the tabs being bent around the outer edges of the flange 310 to secure the outer edges of the clamp to the I outer edges of the flange. It should be noted that the shoulder 12 projects somewhat above the upper surface of the flange 31c as viewed in FIG. 3, so that clamping of the tabs 45a around the flange to bring the outer edges of the clamp and flange together distorts the cover clamp somewhat from its otherwise plane condition with its inner edges separated from the inner portions of the flange. The distortion of the cover clamp 45 results in a biasing force against the shoulder 12 urging the edge 41 of the casing 11 against seat 40 of the diaphragm assembly 30. Accordingly, the resiliently yieldable cover clamp 45 will clamp edge 41 snugly to seat 40 at all times even though shifting of the shoulder 12 relative to the flange 310 may occur as a result of uneven expansion and contraction of the casing 11 and cover member 31 or as a result of permanent shrinking of casing 11 as sometimes occurs with some commonly used insulating plastic materials when subjected to high temperatures. Because the clamp 45 has substantial breadth corresponding to the flange 31c, the actual clamping force will not change appreciably even with substantial differences in expansion, and because the clamp engages the shoulder 12 throughout a substantial length thereof, stresses will be so distributed that the casing will not be subjected to such localized forces as to cause breakage thereof.

Disposed between the glass laminate dielectric disc 27 and the diaphragm 33 is a tapered compression spring 48 having its small end conveniently disposed in a spring cup 49 hearing against the diaphragm. The spring 48 provides a load on the diaphragm 33 which determines the operating pressure characteristics of the switch 10 and biases the diaphragm toward the switch open position. The strength of spring 48 is less than the axial force imparted by clamp member 45 maintaining casing 11 and power means 30 in seated relationship so that spring 48 cannot cause unseating of these parts.

Referring to FIGS. 1 and 5, it will be noted that the switch casing 11 is conveniently provided with raised ribs or keys to align the cover clamp with the switch casing during assembly. The cover clamp 45 is also conveniently provided with apertures 54 which register with the apertures 32 of the flange 310 for convenience in mounting the switch 10.

From the foregoing detailed description it will be appreciated that there has been provided by this invention a novel and improved fluid pressure operated switch comprising cooperating portions formed of materialshaving substantial different coefficients of thermal expansion, united in such a manner that the switch may withstand wide variations of ambient temperatures without damage from different degrees of expansion and/or contraction without loss of reliability and repeatable operating characteri stics, It will also be appreciated that the foregoing is sure actuated switch embodying the invention, it will be understood that the invention is not limited thereto but rather the invention includes all those modifications, substitutions, adaptations, and uses as are reasonably embraced by the scope of the claims hereof.

Having described my invention, I claim:

1. A fluid pressure operated switch comprising:

(a) a switch casing formed of rigid electrically insulating material, said switch casing having one end portion presenting an outwardly facing bearing surface and shoulder means thereon facing in the opposite direction from that of said bearing surface,

(b) switch means in said body,

(c) power means having a part abutting said bearing surface for operating said switch means, means to secure said power means to said bearing surface comprising a generally flat annular flange member projecting radially substantially beyond said bearing surface and shoulder means, a generally flat annular clamp member surrounding said one. end portion of said casing and having inner edges engaging said shoulder means and projecting radially coextensively with said flange member and having the inner portions thereof spaced apart, and means securing the outer edges of said members together one of said members being resiliently flexible axially relative to the other and normally separated from the other at the inner portions thereof whereby said shoulder means and bearing surface are resiliently urged in the directions of one another.

2. A fluid pressure operated switch comprising:

(a) a switch casing formed of rigid electrically insulating material, said switch casing having one end portion presenting a seating surface and shoulder means thereon facing in the opposite direction from that of said seating surface,

(b) switch means in said body,

(c) power means having a part abutting said seating surface and operable to actuate said switch means, means to maintain said power means against said seating surface comprising a generally fiat annular flange member connected with said power means and projecting radially substantially beyond said bearing surface and shoulder means, a generally flat annular resilient clamp member surrounding said one end portion of said casing and having the inner edge portions engaging said shoulder means and projecting radially co-extensively with said annular flange member, and means securing the outer edges of said flange and annular member together whereby the resiliency of said clamp member biases the inner portion of said clamp member toward said flange member, said shoulder being positioned relative to said seating surface to maintain the inner portions of said annular clamp spaced from said flange member.

3. A fluid pressure operated switch comprising:

(a) a switch casing formed of rigid electrically insulating material, said switch casing having one end portion presenting a bear surface and a shoulder adjacent said bearing surface,

(b) switch means in said body,

(c) an expansible power means for operating said switch means, said power means comprising a metal cover member having a laterally extending flange and presenting a seat engaged by said bearing surface of said switch casing,

(d) a resiliently flexible sheet metal clamp comprising a portion overlying one surface of said flange and having an opening receiving said casing, said clamp bearing against said shoulder, and

(e) means to secure the outer edges of said clamp to the outer edges of said flange whereby said clamp operates with a resiliently yieldable force to retain said casing with said bearing surface engaging said seat.

4. A fluid pressure operated switch comprising:

(a) a hollow switch casing formed of rigid electrically insulating material, said switch casing having one end presenting an annular bearing surface and a radially extending shoulder adjacent said bearing surface,

(b) switch means in said casing and having operating means extending axially from said one end thereof,

(c) a diaphragm assembly comprising a metal cover member having an end wall, side wall means extending from said end wall, and a flange extending outwardly from said side wall, a flexible diaphragm defining with said end wall and expansible chamber, said diaphragm assembly presenting an annular seat engaged by said bearing surface of said switch casing with said diaphragm engaging said operating means, and

(d) a resiliently flexible sheet metal clamp comprising a portion overlying one surface of said flange and having an opening receiving said casing, said clamp bearing against said shoulder and having a plurality of tabs bent around the edge of said flange to overlie the other surface thereof, whereby said clamp operates with a resiliently yieldable force to retain said casing with said bearing surface engaging said seat.

5. A flud pressure operated switch comprising:

(a) a cup-shaped switch casing formed of rigid electrically insulating material, said switch casing having an open end presenting an annular bearing surface and a radially extending shoulder adjacent said bearing surface,

(b) switch means in said casing and having operating means disposed in said open end thereof, said operating means being supported for inward and outward movement for actuation of said switch means,

(c) a diaphragm assembly comprising a metal cover member having an end wall, a cylindrical sidewall, and flange extending outwardly from said side wall, a flexible diaphragm defining with said end wall an expansible chamber, said diaphragm assembly presenting an annular seat engaged by said bearing surface of said switch casing with said diaphragm engaging said operating means,

(d) said open end of said casing being nested in said cover member with said bearing surface engaging said annular seat and said diaphragm engaging said operating means, said shoulder being offset to one side of one surface of said flange, and

(e) a resiliently flexible sheet metal clamp comprising a portion overlying said one surface of said flange and having an opening receiving said casing body, said clamp bearing against said shoulder having a plurality of tabs bent around the edge of said flange to overlie the other surface thereof, whereby said clamp operates with a resiliently yieldable force to retain said casing with said bearing surface engaging said seat irrespective of temperature induced changes in size of said casing with respect to said cover member.

6. A fluid pressure operated switch of the character defined in claim 1 in which the outer edges of said members are secured together by tabs formed on one member being bent around edge surfaces of the other member.

7. A fluid pressure operated switch of the character defined in claim 2 in which said clamp member has tabs formed thereon projecting from the outer edges thereof and being bent around the outer edges of said flange member.

No references cited.

BERNARD A. GILHEANY, Primary Examiner. 

1. A FLUID PRESSURE OPERATED SWITCH COMPRISING: (A) A SWITCH CASING FORMED OF RIGID ELECTRICALLY INSULATING MATERIAL, SAID SWITCH CASING HAVING ONE END PORTION PRESENTING AN OUTWARDLY FACING BEARING SURFACE AND SHOULDER MEANS THEREON FACING IN THE OPPOSITE DIRECTION FROM THAT OF SAID BEARING SURFACE, (B) SWITCH MEANS IN SAID BODY, (C) POWER MEANS HAVING A PART ABUTTING SAID BEARING SURFACE FOR OPERATING SAID SWITCH MEANS, MEANS TO SECURE SAID POWER MEANS TO SAID BEARING SURFACE COMPRISING A GENERALLY FLAT ANNULAR FLANGE MEMBER PROJECTING RADIALLY SUBSTANTIALLY BEYOND SAID BEARING SURFACE AND SHOULDER MEANS, A GENERALLY FLAT ANNULAR CLAMP MEMBER SURROUNDING SAID ONE END PORTION OF SAID CASING AND HAVING INNER EDGES ENGAGING SAID SHOULDER MEANS AND PROJECTING RADIALLY COEXTENSIVELY WITH SAID FLANGE MEMBER AND HAVING THE INNER PORTIONS THEREOF SPACED APART, AND MEANS SECURING THE OUTER EDGES OF SAID MEMBERS TOGETHER ONE OF SAID MEMBERS, BEING RESILIENTLY FLEXIBLE AXIALLY RELATIVE TO THE OTHER AND NORMALLY SEPARATED FROM THE OTHER AT THE INNER PORTIONS THEREBY WHEREBY SAID SHOULDER MEANS AND BEARING SURFACE ARE RESILIENTLY URGED IN THE DIRECTIONS OF ONE ANOTHER. 